The present invention relates generally to apparatus for manufacturing helically coiled continuous elements for a slide fastener and more particularly to a device for shaping and transporting such fastener elements at increased rate of speed.
As is well known in the art, slide fastener elements in the form of a helical coil are formed by winding a starting linear filament around a mandrel in a coiling machine and set with heat while the filament is progressively advanced. A prior art device for this operation was provided generally with a pair of spaced, parallel screws rotatable on opposite sides of a mandrel and adapted to shape and advance the filament as the latter is progressively coiled around the mandrel. However, the device has suffered from the drawback that screws of the type described rely for their rotation on a relatively small drive member such for example as gear wheel, spindle and the like, which lacks sufficient mechanical strength to withstand at high speed revolution. Another deficiency of this prior art device was that since the screws as well as the mandrel need be long enough to provide sufficient length of time for the heat-setting of fastener elements on these components when operated at high speed, the mandrel becomes susceptible to torsion and is further subjected to severe sliding friction when moving forward the fastener element. Therefore, such prior art device was not suitable for high-speed operation and imposed limitations to the size of the fastener element that can be produced thereby.